Speaking outside court, Tomlinson's stepson Paul King said the not guilty verdict was "a joke".

Harwood was acquitted of killing 47-year-old Tomlinson by striking him with a baton and pushing him to the ground as he walked away from police lines during G20 protests in London in 2009.

King said: "In April 2009, along with everyone else, we saw the shocking video of Ian being violently assaulted by PC Harwood, just minutes before he died.

"After the unlawful killing verdict at the inquest last year, we were expecting to hear a guilty verdict, not a not guilty verdict. It really hurts."

King said the family was not giving up on justice for Tomlinson.

"There has to be one more formal and final answer to the question: who killed Ian Tomlinson? That will now be pursued in the civil courts," he said.

"The last three years have been an uphill battle, we've had to deal with many obstacles, setbacks and emotions on the way. "It's been very hard to keep going and we took strength and support from everyone, from the public."

He thanked the medical student Lucy Apps, who tried to save his stepfather's life after he collapsed.